Question

Which of the following is an example of top-down approach for the preparation of nanomaterials?

(a) Gas phase agglomeration

(b) Molecular self-assembly

(c) Mechanical grinding

(d) Molecular beam epitaxy

The question was posed to me in class test.

This question is from Nanotechnology topic in chapter Materials and their Properties of Engineering Chemistry I

Answer 1

Right answer is (c) Mechanical grinding

Easy explanation: Mechanical grinding is an example of top-down approach for the preparation of nanomaterials. All the other options are the example of bottom-up approach.